I have watched a lot of quilting shows and have heard that storage in plastic boxes and bags should only be for two years, max. I live in Houston, Texas --- a very humid area. I have a lot of fabric in plastic bags and plastic storage containers which are in a spare bedroom. I often rumage around in them and leave the tops off so I have not had any problems --- yet. Now we do run the A/C a lot of days --- not because the temperature is high --- but because the humidity is so high. Personally, I think anytime fabric are closed up in anything for a long period of time, they get a mildew smell. My sister in Austin, Texas (a really dry area) brought me some fabrics which had been stored several years. I let them air out for several days. Sometimes, I just want to give up on house work and do nothing but sew up all the fabric I have then I would not have to worry about storage.